|Name:||Ng Ka Yiu Minnie|
|Year:||2017 – 2018|
|Geological Age: (Fossil) (Rock)
Chemical composition, bonding and structure: (Mineral)
Sedimentary rock :limestone
那裏的沉積物通常很少衝入海所以那裏的水質非常清澈並提供一個非常適合的地理位置給石灰岩的形成。當海洋生物死後屍體在海底沉積。多年後，屍體會將被 上面所覆蓋的其他沉積物擠壓 使其變成固體 稱為沉積岩(海百合石灰岩)。他亦因為他的外貌被人稱為德比郡螺絲。
Living Specimens: (Fossil)
There was very little sediment washed into the sea. The water was therefore very clear, and this produced perfect conditions for the formation of limestone. When these sea creatures died, it deposited in the sea after hundred years the dead sea creatures will be compressed by the weight of the overlying layers(compaction) then both compaction and cementation help transform loose sediment and fossil into solid rock called sedimentary rock (Crinoidal limestone). It have been referred to as “Derbyshire Screws” because of their appearance.
It contains bivalves, brachiopods, corals and crinoids in a fragmental matrix cemented by crystalline calcite (known as sparite).
Crinoids are sea animals that had long stems, cup like bodies and long filter arms, that look so much like flowers that they are call sea lillies. The stems breaks into small, disc shaped fragments.
|Application: (Rock) (Mineral)
These specimens can be made into unusual organic gems.
|Distribution: (Rock) (Mineral)
Although some of the seas are shallow and rich in nutrients which provides a favorable condition for the formation of sedimentary rock but still there are some of the crinoidal limestone found far from the sea.
Some of the crinoidal limestone are found in England and France.
These are found extensively in eastern Kansas. The Cretaceous Niobrara Chalk is one of the few localities in western Kansas that contains beautiful specimens of stemless crinoids, in which both the bodies and the long arms are well preserved.